Engine ignition and power testing apparatus



July 13, 1948- I R. L. SEXTON 2,445,245

ENGINE IGNITION AND POWER TESTING APPARATUS Filed Aprii 16, 1945 2 Sheets- Sheet 1 ATTORNEY y 1943- I R. L. SEXTON 2,445,245

ENGINE IGNITION AND POWER TESTING APPARATUS Filed April 16, 1945 2 Sheets-Sheet 2 v INYENTOR Poss/2T L. $Ex7'0/v Patented July 13, 1948 UNITED STATES PATENT OFFICE ENGINE I Z JZQWER TESTING L APPARATUS Robert L. Sexton, Flushing, N. Y. Ap l c ion A rilv 1.6 1945, Se al No- 588 565 3 Claims. 1

it i e trem l imno ta in: moder n e combu tio en in s a especially a ra ngines that th same he k t pe a e iently an w th: as sho t hu d n fo r as possible. Theinyestrnent in; modern large airp anes. i so sr e hst it i ecess ry to e p e plan sin th air aen ol;. i et y sev nt p nt of he time n or er tore ou h investmen made in the airplane, and hence it becomesvery important that engine overhaul periods b sho t ned as much a po sib When it is realizedthat ignition troubles are the cause of more en ine fa lures than a y oth r factor, the importance of easily detectin and locatin i nit on troub s. be m s ry-appa e t- The. present methods ofshoqting. ignition trouble are arduous andconsum con id ra etime. or example; a sumin an eie te nrcylimi airc en i is. "rough on th ef ag t which would tend to indicate that a rear plug is fouled, in that cas under the present syst m of testin eighteen 'sparkplugs are usually hanged, where actually onlyoue plug, is at fault. This makes ignition repair w rk on airplan neine n t on y a. lengthy matter. but also eignensive. Furthermore,.eyl1nders veryoiten fall off in power an upto thev time citrus-invention it was impossible to determine readily J'llst which cylinder was falling off inpower and to what extent. Furthermore, faulty ignition results; in local, radio inter.- ference; which is highly obj ctionab e. e pec l in aircraft. I I g The applicant. hereof has disoovered means whereby the ignition. of any one selected cylinder maybe isolated; so to speak, even. while the engine is running, and tested for faulty action. In the event of suchfaulty action, it known definitely just where the trouble lies, so thatgcare= ful and tediousexamination of all spark 'plugs in all cylinders is unnecessary. i important featur of th present inv ntion is: to Pr i e no e en n i nition a d: P wer es in a paratus which ena l s he cos ne P" stator to 91st; any cylinder in hich? e is il 'fifilfifitli in ill by merelwre sing huttqll 2 determine whether or not the ignition in that cylinder is faulty. In the event of dual ignition, t r ss r of wo bif ons l e e e whether or not the ignition of the cylinder is 5. iau t her u n the. pre sin o he' o tons alternately will determine which Pl in such cylinder is faulty, so that an, airplane operator is. a le to note. even while in fi ehtjjw h oi he thirt -six pl s n an igh cy r 10 en ine is .tau ty by me y pre ng. tton thereb enab i h r pl c m n f Single 1*?- festive. pl s withou laci ei h een Pl A. f r h r f ature of th pr s nt inv nt on s t p o e t e uip nt. tor h ckin on he torque and power output of any desired cylinder o a en e or example, if t ha pens to be an. ht n-c inde en ne h engine e at may select any cylind r a de mi its tor ue a power utput- In that wa h read y det r:

mine Whether a y nde p rform ng p o er y, and there y f r tell failures. i Very often a cylinder will gradually fall off n power, an his mayb t I a n mber ofy nd rs, so th the eral ow of t e n ine falls 0. and yetthe. trouble is not suf iciently had to Warrant complete overhaul of the engine. By using. the test equipment of the presentinyen tio a y li r or c lind f l in Off in power can be quickly detected and correction made. Furthermore, detonation resulting in loss ofpower can be detected and. located.

. A further feature of. the present invention is to provide a small, inexpensive, compact, and l t t t e p en h t is ea l anp led 0 3 existing engine installations, and is easily op: erated for testing. and locating. ignition troubles and defective cylinders, even while the engine is running, thereby greatly decreasing the maintee nance time heretofore required in servicingaire planes and cutting; the cost of maintenance en mou y Other features and advantages will hecomeap patient from the specification, taken in connece tion with the accompanying drawings wherein the invention is embodied in concrete form.

In'the drawings, I Fig. 1 is a schematic view of the-novel engine ignition apparatus of this invention shown, as applied. to a o -cylin er n ine;

ll s- 41A. is a diagrammatic view sh w nstlis numeral 5 designates a contact breaker cam of the engine magneto which, as shown in Fig. 1A,

may be magneto 6 or 1. The cam 5 is adapted to actuate the breaker arm 8 for opening and on the periphery of the bell housing 24.

Fig. 3) corresponding to the number of cylinders shown in the structure of Fig. 1, wherein a fourcylinder engine is involved, which numerals correspond to and are arranged in the firing order of the engine cylinders. The open mouth of this bell housing fits into a circular depression 31 provided in a plate 38 attached to the end of the magneto housing 39. The bell housing has a radial lip or flange 40 that is engaged by springpressed washers 4| carried by screws 42, which serve to retain the open mouth portion of the bell housing in assembled relation with the plate 38 and rotatable with respect to this plate. An index member or pointer-"43 is carried by the plate 38 for cooperating with the marks I, 2, 3, and 4 Obviously, if the engine had eighteen cylinders, there closing the contact breaker points 9 located in the circuit of the primary winding I0 of the magneto. As is customary, when the primary contact points 9 open, the flow of primary current through coil I 0 is interrupted, causing an' extremely rapid change in flux linkages, resulting in the production of a high voltage in the secondary winding II of the magneto, which voltage is supplied through lead I2 to the distributor finger I3 for passage through distributor contacts I, 2, 3, and 4 and connected high tension leads I4, I5, I6, and I! to engine spark plugs I, 2', 3', and 4'. So far the structure is typical of an engine ignition system.

In its preferred form, the apparatus of the present invention is an attachment comprising an auxiliary cam shaft I8 havin an enlarged hollow inner end portion I9 which fits Within a recess provided in the outer end of the magneto breaker cam 5 (see Fig. 2), the said auxiliary shaft I8 having a driving block or key 29 adapted to fit into a slot provided in the end of the contact breaker cam 5, whereby this breaker cam drives the auxiliary cam shaft I8.

Shaft I8 is mounted on a rotor-bearing block 22 which abuts the enlarged end portion I9. Bearing block 22 'is longitudinally slidable 'in slide-bearing aperture 23 provided in a bell housing 24. A screw 25 extends through housing 24 andprojects into a longitudinal groove 26 in rotor bearing 22, thereby serving to prevent the turning of this bearing while permitting longitudinal movement thereof. A coil compression spring 21 presses on the rotor-bearing block 22 and hence urges the enlarged end portion IQ of shaft I8 inwardly toward and into engagement continuously with the contact breaker cam 5 to be driven by the latter.

The enlarged portion I 90f auxiliary cam shaft I8 is provided with a peripherallongitudinal cam groove or depression 28 (see especially Fig. 4) which cooperates with a cam follower 29 that serves to actuate a pair of breaker points 30. So long as the follower 29 is riding on the high surface 28' of the cam shaft portion I9, the follower 29 holds the breaker points 30 disengaged by flexing arm 3| upwardly. However, when the cam groove 28 rides under the follower 29, this follower drops down into roove 28 and allows the resilient arm 3I to move downwardly, thereby engaging points or contacts 30 as shown in Fig. 4. These breaker points are connected at one side (see Fig. 1) through a lead 32, condenser 33, push-button 34, and lead to one side of the primary winding III The other side of the breaker points 39 are connected by lead 36 to ground.

The bell housing 24 is show on its exterior surface provided with numerals I, 2, 3 and 4 (see would be eighteen'numbers on the bell housing 24.

I '1 An outer end cover or knob 44 is fixedly mounted ,upon the bell housing 24 and has a knurled outer surface 45 which may be grasped for turning ,this, bell housing so that any particular cylinder number, such as I, may be aligned with the pointer 43 as shown in Fig. 3. With such position of the bell housing, the cam follower 29 is so positioned angularly with respect to the contact breaker cam 5 and cam groove 28 of the auxiliary cam that when cylinder I of the engine fires, the cam follower 29 will drop into cam slot 28, thereby closing contact points 30 at the very moment that the spark plug in cylinder I fires. However, this action has no effect so long 'as the push-button 34 is open. If push-button 34 is held closed, thenevery time cylinder I is about to fire both sides'of the primary winding II] will be grounded because (referring particularly to Fig. 1) with the contact points 39 closed and switch 34 closed, the lower side of the primary winding I0, as shown in Fig. '1, is grounded and its other side is always grounded, and so no voltage is induced in the secondary'II and consequently the plug or cylinder I Will receive no secondary current and hence will not'fire. I

Likewise, if the knob 44 is turned so as to bring the number 2' on bell housing 24 opposite pointer 43, then each time that cylinder number 2 fires, the contact points 30 will be closed, and if the push-button 34 is also closed at that time, the plug or cylinder number 2 will not fire since both sides of the primary winding II] are shorted.

' When applying the device to a dual-ignition engine as shown in Fig. 1A, two sets of contact points 30 and 30 are employed and likewise two push-buttons 34 and 34 are employed, leads '35 and 35' connecting to the primary windin of the two magnetos I5 and I. Only two high tension leads of these two inagnetos are shown in Fig. 1A connected to a single cylinder, but it will be understood that leads are connected to each of the cylinders. A switch 46 is shown for permanently grounding the primary ll] of the magneto when desired. In Fig. 1A, the auxiliary cam shaft I8 is shown driven directly from the engine through reduction gearing 56 instead of from the magneto.

A torque meter is attached to the engine to indicate the brake means effective pressure (B. M. E. P.) or the pressurecomponent of torque in pounds per square inch. This torque meteris illustrated as comprising a sun gear 48, which is attached by linkage 49 to a plunger 50 working within hydraulic cylinder 5I which is supplied with oil under pressure by pump 52, and a pressure gauge 53, which may read directly in torque applied to the propeller is transmitted" through pinion 54 and gear-4flto plunger 50, whereby meter 53 reads the. torque ofthe. engine or may be calibrated in pressure units, if'de'sired,

From the readingof meter 53,- the brake horsepower of the engine can be readilyscalculatedas follows:

- B. H. PM

wherein T represents the torque. In operation, to determine whether or not the spark plug of a cylinder is functioning properly, it is merely necessary to turn the knob 44 until the desired cylinder number, such as number I, is opposite the index 43 as shown in Figs. 1 and 3. The brake mean effective pressure (B. M. E. P.) is read from the torque meter 53. The push-button 34 shown in Fig. 1 is then depressed so as to ground both sides of the primary l0, thereby shutting off the high tension power to the plug of cylinder l. The B. M. E. P. reading of meter 53 is again noted during the ignition cutout of cylinder l. The difference between the first B. M. E. P. reading and the second represents the loss in torque, which can be converted to horsepower as follows:

For a good cylinder the value of B, H. P. Lost should equal 13. H. P. K

where K equals the number of cylinders of the engine. If there is no falling off of the indicated B. M. E. P. when closing the push-button 34, the particular cylinder being tested is not putting out power. If the cylinder is operating properly there should be a drop in B. M. E. P. which is equal to the original B, M. E. P. reading divided by the number of cylinders in the engine. Thus, this testing device is very rapid in its action and cylinders can be tested as rapidly as the engineer can turn the knob 44 to successive cylinder num- "bers and press the button 34 and read the meter Where dual ignition is used, as shown in Fig. 1A, to locate the cylinders having faulty ignition, both buttons 34 and 34 are pressed or closed simultaneously, thereby grounding the corresponding plugs of cylinder l, for example, simultaneously, whereupon the fall in B. M. E. P. is noted. If no fall is indicated, obviously no power is being received from that cylinder, which indicates any one or more of the following difficulties:

a. Poor compression,

b. Both spark plugs fouled simultaneously (very rare),

0. Mixture not reaching cylinder,

d. Spark plug wires broken or not hooked to plugs.

Assuming that the B. M. E. P. does fall to some extent when both plugs are grounded, the next step is to ground one plug, for example, the front plug ohly; by closing switch 34 alone;- If now the-B; EI'P. doesfall'ofl', the rear plug'has faultyignition, andif the B. E; Phdoes not' fall, the rear plug and ignition is all right. The

- push buttondfi is nowclosed; therebygrounding the rear plllg, and-thesame procedure is rep'eated;

thereby determining whether the front plug is:

flring properlyw Thus it is readilypossi'ble todetermine which cylinder is not functioning properly, and-ii it is' dual ignition it is' readily deter minable as-to which of the two-ignition systems is at fault" aswell as the particular plug which is In making power tests, the engineer will press both buttons 34 and 34' simultaneously and note the B. M. E. P. drop, thereby determining the power output of any particular cylinder by the change in B. M. E. P. reading. By pushing the button 34, controlling the front plug, we can test the rear plug ignition, and by pushing the button 34', controlling the rear plug, we can test the front plug ignition.

The apparatus of this invention also serves for determining the location of faulty ignition causing radio interference. Where a dual-ignition system is employed, each magneto is grounded in turn by closing switches 46 and 46' in succession. By grounding switch 46, if the interference ends, it is known that the ignition trouble is in the system associated with switch 46. If the trouble still persists, then it is the ignition system associated with switch 46. Each plug of the faulty ignition system is then grounded in turn to determine which plug is faulty. The connections to this plug are then checked as well as the plug to detect loose connections. Thus, it will be seen that merely by pressing buttons 34 and 34' the engineer can quickly determine which cylinder of a multi-cylinder engine is not functionin properly and then readily locate the plug of that particular portion of the ignition system which is at fault, thereby enabling the replacement of one plug instead of many plugs and eliminating the hunt and try methods at present employed.

Since many changes could be made in the above construction and many apparently widely different embodiments Of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1, Engine and ignition power testing apparatus r comprising an auxiliary cam driven from the engine, contact points actuated by said auxiliary cam, a housing for carrying said contact points, said housing being angularly adjustabl with respect to said auxiliary cam to thereby effect the closing of said contact points simultaneously with the firing of any selected engine cylinder, a circuit connecting the engine ignition through said contact points to ground, switch means in said circuit for closing said circuit to cut off the ignition of such selected cylinder, and a torque indicator operable from the engine, for showing changes in the torque output of the engine responsive to the operation of said switch means.

2. In apparatus of the character described for testing of engine cylinders, contact means connected at one side with the engine ignition and at the other side with ground, adjustable means for setting said contact means for operation in synchronism with the firing of any selected engine cylinder, whereby the ignition of such cylinder is selected cylinder.

-3. Apparatus for shutting off the supply of high tension currentto engine spark plugs during engine operation comprising a grounding circuit electrically connected with the spark plugs,-sai'd' circuit comprising make and break contact members actuated from the engine and switch means for completing said circuit, means for adjusting said contact members for causing actuation ,of the same in synchronism with the firing of any selected spark plug, whereby the closing of said switch means serves to shut off the current to the spark plug selected, and a torque meter driven from the'engine for indicating change'in engine torque upon the closing of said switch means.

ROBERT L. SEXTON.

REFERENCES CITED The following references are of record in the m file of this patent:

FOREIGN PATENTS Country Date Great Britain Mar. 18, 1920,

Number 

